Ceramic materials like alumina and zirconia are widely used at present, have the characteristics of corrosion resistance, oxidation resistance, and big specific surface area, and can be used as absorbent, catalyst carriers, composite material reinforcer, high-speed cutting tools, medical materials, and anti-wear parts. A carbon nano tube has multiple advantages of big specific surface area, ultra-high modulus, high intensify and good conductibility, has wide application prospect in multiple fields including high-performance composite materials, medical materials, and electron field emission devices, has wide application prospect, and can also be used as an alumina reinforcer to improve the properties of the alumina like conductivity and catalytic activity, etc. However, because the carbon nano tube has one-dimensional nanostructure characteristics, the length-diameter ratio is large; meanwhile, because of the large Van der Waals force and huge specific surface area between carbon nano tubes, the carbon nano tube is easy to exist in a tangled aggregate. How to prepare and disperse the carbon nano tube in the alumina powder becomes a key factor to play the excellent performance of the carbon nano tube.
At present, there are more preparation methods of carbon nano tubes, including a catalytic cracking method, a chemical vapor deposition method, a template method, or the like. When preparing alumina-carbon nano tube composite powder, metal nanoparticles (catalyst) are firstly mixed with alumina in general, and then carbonaceous gases like methane and acetylene are fed, to form a carbon nano tube through thermal decomposition. Lee et al, prepared alumina nanowires and carbon nano tubes by filling alumina inside the carbon nano tube and covering the carbon nano tube on the surface of the alumina through a chemical vapor deposition method [Lee J et al. Journal of Crystal Growth, 2003, 254(4): 443-448]. Some researchers prepared or purchased the carbon nano tube, and then directly mixed the carbon nano tube with alumina to obtain composite powder. For example, Ahma et al, purchased a commercial carbon nano tube, then chemically modified the multi-wall carbon nano tube by using H2SO4—HNO3 acid mixture solution, and added surfactant and □-Al2O3 for ultrasonic dispersion, and then dried the mixture for standby. (Ahma et al., Materials Characterization, 2015, 99: 210-219). In the patent published by Wu Xiwang et al (Chinese Patent Publication Number: CN 103979942 A), a carbon nano tube and alumina powder were added into fused thermoplastic polymer melt to stir and mix; the mixture was added into a double screw extruder or a single screw extruder to extrude and disperse till it is stable; the extruded material was degreased under a high temperature to remove polymer materials and obtain carbon nano tube-alumina composite powder. An in situ producing method has the advantages of simple and convenient preparation and low cost, and has aroused widespread concern. Zhang Xinghong et al, invented a method for synthesizing carbon nano tube modified ultra-high temperature ceramic hybrid powder in situ (Chinese Patent Publication No.: CN 104016685 B), which sufficiently dispersed a catalyst in an organic polymer precursor to obtain mixed powder firstly; then put the mixed powder obtained into a square mold of which the upper part was open, heated the power in a tube furnace for cracking till the complete ceramization temperature of the organic polymer precursor was 1450 to 1550□, and carried out heat preservation for 0.5 to 2 hours; then naturally cooled the powder to 20□ to 25□, thus obtaining the carbon nano tube modified ultra-high temperature ceramic hybrid powder. However, the method still has the problems of complicated steps and high processing temperature, etc.